1. Field of the Invention
This invention relates to outsoles, shoes and methods of manufacture thereof, and more particularly to partially fabric outsoles, shoes bearing such outsoles and methods for manufacture of such outsoles and shoes.
2. Description of the Related Art
The outsole of the shoe is the exposed portion of the sole that contacts the ground or other supporting surface. In a shoe, generally the outsole is attached to a shoe “lower,” which in turn is attached to the shoe “upper.”
Shoes are generally classified based at least in part upon the materials of the upper and the outsole into various classes under Chapter 64 of the United States Harmonized Tariff Schedules. That classification then determines the rate of duty to be assessed on the shoes as they are imported into the United States. Thus, the material of the outsole can often determining the rate of duty which is to be applied to the specific shoe.
Depending on the material used to manufacture the upper and the outsole, the rate of the duty may vary significantly. For example, the rate of duty may range from 37.5% ad valorem for many common types of footwear to 3% ad valorem for certain types of sandals and similar footwear. Particularly advantageous rates of duty for rubber soled shoes can be obtained if 50% or more of the bottom surface of the shoe (outsole) that contacts the ground is fabric.
Therefore, a variety of techniques have been developed for partially coating or covering a shoe outsole with fabric or producing a shoe with such an outsole. Many of such techniques have been patented. For example, U.S. Pat. No. 7,451,511 describes a seven-step process for preparation of a partial fabric-bottom shoe sole. In its broadest conception, the process comprises: a) covering a sheet of fabric with TPU (thermoplastic urethane) by superimposing the fabric sheet with a sheet of TPU; b) heating the TPU sheet to its melting point to adhere it to the fabric sheet; c) cooling the TPU-covered fabric; d) cutting the cooled TPU-covered fabric to fit a backing member; e) positioning the cut, cooled TPU-covered fabric into the bottom of a mold; injecting TPR (thermoplastic rubber) into the mold at a temperature below the melting point of the TPU, but high enough to render the TPU tackily adherent to the TPR; and g) cooling the resultant outsole.
U.S. Pat. No. 6,571,491 describes a method of manufacturing a shoe outsole that comprises inserting a fabric material into a first mold, injecting a first material into the first mold and operating the first mold to form a reinforced fabric material, inserting the reinforced fabric material into a second mold, injecting a second material into the second mold and operating the second mold to form the outsole to produce an outsole that includes an exposed, ground contacting surface comprising a first section formed of the second material and free of fabric material, and a second section formed of the reinforced fabric material. The patent also describes a method of manufacturing a shoe by attaching a shoe lower to a shoe upper and attaching an outsole having a ground contacting surface to the shoe lower and produced by the method described in the patent for producing the outsole.
U.S. Pat. No. 6,430,844 describes a shoe such as a slipper with at least a partially fabric bottom, but provides little guidance as to how it is produced. The shoe described in the patent comprises an outsole that consists essentially of an inner backing part of a shape-retaining, moldable material, and an outer fabric part of a fabric material different from the shape-retaining material. According to the patent, the outer fabric part is retained and held in shape and position by the shape-retaining material of the inner backing part and the inner backing part is molded in a common mold in situ with, and integrally embedded in, the outer fabric part to resist separation of the different materials and to resist shape distortion of the outer fabric part. Further, a cushioning element overlies and is non-moldably attached to the outsole and an upper is non-moldably attached to the outsole.
U.S. Pat. No. 6,696,000 is a division of the application that issued as U.S. Pat. No. 6,430,844 and so its specification also contains little guidance for how to make the shoe of that patent, but nevertheless claims a method of making the shoe. According to the claims of U.S. Pat. No. 6,696,000, the method comprises the steps of a) molding a molded shoe outsole with an inner backing part of a shape-retaining, moldable material and with an outer fabric part of a fabric material different from the shape-retaining material, the molding step being performed by placing the outer fabric part in an injection mold, and by injection molding the inner backing part in situ with the outer fabric part in the injection mold; b) continuing the injection molding step until at least the inner backing part is integrally embedded in the outer fabric part in order to resist separation of the different materials and to resist shape distortion of the outer fabric part which is retained and held in shape and position by the shape-retaining material of the inner backing part; and c) attaching a shoe upper to the molded shoe outsole subsequently to, and independently of, the molding step.
U.S. Pat. No. 7,179,414 claims a method of manufacturing a shoe that comprises the steps of: a) inserting a sheet of fabric material into a first injection mold; b) injecting a curable, flowable, thermoplastic material into the first mold into contact with the sheet of fabric material for bonding therewith upon curing to form an integrated fabric-thermoplastic part; c) removing the integrated fabric-thermoplastic part from the first mold; d) inserting the integrated fabric-thermoplastic part into a second mold; e) injecting a curable, flowable thermoplastic material into the second mold into contact with the integrated fabric-thermoplastic part for bonding therewith upon curing to form an outsole; f) removing the outsole from the second mold; and g) independently non-moldably attaching a shoe upper to the outsole at a site at which molding is not performed.
Other patents show various partial fabric-bearing outsoles and methods for preparation of them as well. Each of the techniques, outsoles and shoes shown in the patents noted above and the other patents involve various disadvantages. For example, the industry is always searching for lower cost materials and manufacturing techniques, as well as lower energy consumption and more environmentally friendly methods for manufacturing partial fabric-bearing outsoles.